Photographic light unit



April 17, 1951 E. B. NOEL 2,549,330

PHOTOGRAPHIC LIGHT UNIT Filed April 15, 1947 lnv erwTor-z Edward B.' Noel.-

y WMJ WW His A'I'Tore L Patented Apr. 17, 1951 signor to General Electric ration of New York- Company, a corpo- Application April 15, 1947, serial No. 741,632

I 6 Claims.

My invention relates to lighting units for photography and is of particular interest in connection with such units comprising two lamps assembled-so as to have a common light center. Units of this type are available commercially and comprise an incandescent lamp to furnish lighten the subject before the photograph is taken and an electric discharge lampwhich emits an intense flash of actinic light by which the photograph maybe taken. The discharge lam is inthe form of a helically coiled tube and the incandescent lamp is mounted coaxially with the tube and the jacket. A lamp unit of this type is disclosed and claimed in copending application Serial No. 503,068, filed September 20, 1943, by Paul B. Davisand myself which application is assigned to the same assignee as the present application and is now Patent No. 2,469,607, issued May 10, 1949.

In the unit disclosed and claimed in the patcut the discharge tube and the incandescent lamp are supported from a base which is attached to the open end of a light transmitting tubular jacket surrounding the two light sources.

The base has five contact prongs through which electric power is supplied to the lamps and by which the'unit may be mounted on a suitable holder.

An object of my invention is to simplify the structure and increase the safety factor and convenience in use of lighting units including lamp units and holders of the above type. Various features and advantages of the invention will appear from the following description thereof and from the claims. I

In the accompanying drawing, Fig. 1 is an. elevation, partly in section, of a lighting unit embodying my invention, and Fig. 2 is a bottom view of the holder shown in Fig. 1.

Referring to the drawing, the lighting unit comprises three main members: The holder I, the incandescent lamp 2 and the discharge lamp unit 3. The latter is madeup of a light transmitting tubular jacket 4, an annular base 5 and a helically coiled discharge tube 6 of glass or quartz containing a suitable ionizable atmosphere, such as a filling of xenon, and having a cathode 1 and an anode 8 sealed in its ends.

The base 5 is cemented to the open end of the jacket and is provided with contact prongs 9, I0 and II towhich are attached metal wires I2, I 3 and I 4, respectively, which form a rigid framework in the form of a cylindrical enclosure for supporting the tube 6 axiallywithin the jacket 4 and through which electrical energy is supplied through contact prongs 9 and I0. emits a flash of actinic light of high intensity I0 and II pass through openings in the annular support plate or disc I5 of the holder I and the portions of reduced section thereof are re,- leasably engaged by spring clip type electric contacts I6, I! and I8, respectively, in registry with the openings and secured to the bottom of the disc I5 (Fig. 2) which consists of electrically insulating material. The holder contacts I6, I! and I8 are arranged in a circle concentric with a socket I9 mounted in the center opening of the sup ort disc I5. The socket I-9 accom-v modates the bayonet type base 20 of the incandescent lamp 2 which is thus supported by the holder I independently of the discharge lamp unit 3 and coaxially with the said unit so that the two light sources, that is, the discharge tube 6 and the axially extending filament in the incandescent lamp 2 have the same light center. In such units, the electrical energy supplied to the discharge tube 6 is at a higher voltage than that supp ied to the incandescent lamp 2. The highest voltage is impressed on the lead I4 which is in contact with the discharge tube 6 and, when charged, ionizes the gas in the tube 6 to cause a discharge between the electrodes 1 and 8 which are connected across a condenser The discharge for photographic purposes. A suitable circuit is disclosed in Patent 2,277,697 to H. E. Grier.

In accordance with my invention, the contact prong I I for the high voltage lead I4 is spaced a greater angular distance from the prongs 9 and I0 than the angular distance between prongs 9 and II] for safety purposes. Also, an electrically insulating sleeve 2 I surrounds the socket I9 for the incandescent lamp 2 and extends beyond both ends of the socket I9 a sufficient distance to prevent'electrical flash-overs between the incandescent lamp socket I9 and the holder contacts I6, I! and I8 on the one hand and between the current lead wires I2, I3 and I4 of the discharge lamp base 20- or the socket I9 on the other hand. This increases the safety factor of the lighting-unit. The upper end of the sleeve 2| extends an appreciable distance beyond the top of the base 20 in the socket I9 and the lower end extends an appreciable distance beyond the two set-screw contacts 22 on thebottom of the socket I9 by which the incandescent lamp 2- may be connected across the terminals of a posed between the closely spaced contacts 22 to prevent short circuits between them.

The sleeve 2| is held in place on the support disc l by its shoulder 24 butting against the electrically insulating annular disc 25 cemented to the disc l5 and by a retainer ring 26 of electrically insulating material which makes a frictional fit with the; sleeve 21 and is fastened to the disc l5 by a plurality of bolts one of which, 21, is shown in Fig. 1. Set screws also may be used to secure ring 26 to sleeve 2!. The ring 26 increases the length of the pathbetween the contact II and the contacts 9 and lD.to decrease the possibility of flashover between these contacts. The disc 25 covers and electrically insulates the top of rivets 28 holding the contacts 16,11 and I8 onthe disc l5. a frictional fit with the sleeve 2| and is also held in place by a retractable pin 29 (Fig. 1) extending from its interior into the wall of the sleeve 2i.

The supporting structure for the helically coiledenvelope of the discharge device, comprises spud wires 39 extending laterally from the current inleads l2 and i3 engaging the adjacent topand bottom coil of the tube 6, and tie wires (not shown) looped around the turns of the tube and secured as by welding, to the inlead l serving'as the triggering electrode for the discharge tube. The inlead [4 (part only of which is shown in the drawing) extends upward from the contact prong Ii on the'base 5, thence across the top of the coiled tube 6 and then downward toward the base 5. The last mentioned part thereof: is shown in the drawing. Spring strip braces 31- which are welded to the upper end portions of the inleadsl2, l3 and I4 and which engage the enclosing jacket 4 serve to give additional support to the: helical tube 6 as disclosed in my' copending application Serial No. 716,936, filed December 18, 1946'.

What I'claim as new and desire to secure by Lettersv Patent of the United States is:

1*. A lighting unit'comprising, in: combination, alamp holder provided with a socket for an incandescent lampba-se and. a plurality of electric. contacts arranged around; the. socket, an incandescent lamp removably mounted in the socket;,and,a, lamp unit comprising an, annular base surrounding the socket and, provided with electric; terminalsremovably engaging the holder contacts, conductive supportsextending upward from said annular base to definea cylindrical enclosure and a helically coiled. discharge tube mounted on the supports and within the" ensurrounding and extending beyond both ends of the socket tov insulate the socket. and the lampbase fromconducting. parts of the lighting unit, an incandescent lamp removably mounted in. the socket, and a. lamp unit comprising an annular base surrounding the socket and. the insulating tubeand provided with electric terminalsiremovably. engaging the holder contacts,

conductive supports extending upward fromsaid annular'base to. define: a cylindrical enclosure and; a helically coileddischargectubep mountedon the supports and within the enclosure and The socketzl flimakes.

being coaxial with and surrounding the incandescent lamp so that the two light sources of the unit have the same light center.

3. A lamp holder comprising an electrically insulating annular support, a socket for an incandescent lamp base mounted in the opening in the. support and a plurality of electric contacts mounted in a circle on the support concentric with the socket for engaging electric terminals of an annular lamp base and holding the annular base aroundsaid socket, and an electricallyinsulating sleeve surrounding the socket. and extending beyond both its ends to insulatev the socket. and the base accommodated thereby from the; contacts on the support.

4. A lamp holder comprising an electrically insulating annular support plate having openings around its center opening for receiving contact prongs, a socket for an incandescent lamp base mounted in. the center. opening in the plate with its' base-receiving, part opening in adirection transverseto theplate and a plurality of electriccontacts mounted on the surface of the plate facing away. from the direction in which the socket opensand each being in registry with a prongereceiving opening. in the plate so asto engagev a contact. prong inserted through said opening.

5. A lamp. holder comprising an electrically insulating annular support, a socket for an incandescent lampbase mounted. in the opening in the support and aplurality of electriccontacts mounted in a circle on thesupport concentric with the socket for engaging electric terminals of, an, annular lamp base and holding the annular. base around said socket, and an electrically insulating'sleeve surrounding the socket and extending beyond its ends to insulate the socket andthe base accommodated thereby from the contacts, on the support, saidsleeve also being interposed between one and the. other of said: contacts toincrease-the insulation therebetween.

6. A lamp holder comprising an electrically insulating annular support platev having open-- ings arranged in a circleconcentric; with its center'cpe-ning for receiving con-tact; prongaa socketfor an incandescent lamp base mounted in: the. center opening of said platewith. its: pa-segreceiving; part opening in a, direction transverse to the plate;for the receptionofa lampibase therein and; a plurality of electric contacts mounted on the surface of, the plate facing: away from. the direction in. which said socket; opens. and; each being in registry with. a. prong-receiving. opening. in the plate so as-to' engage a:.contact prong inserted. through. Said'opening, an. el'ec trica'lly. insulating. sleeve surrounding: said socket, extending beyond both of its ends. and inter.-

. posed between said contactstoainsulate-thesocket and; the. lamp. base received. thereby: from. said. contacts and: said; contacts from each. other;

EDWARDEB. NOEL.

REFERENCES CITED- The following referencesare of record in the: file of this. atent:

UNITED" STATES. PATENTS 

